Method for controlling a radio access bearer in a communication system

ABSTRACT

A radio access bearer in a mobile communication system is controlled by disposing a radio resource control layer having radio access bearers in a user side, disposing a radio link control layer, a media access control layer, and a physical layer in the user side beneath the radio resource control layer in succession, measuring a traffic volume of the media access control layer and radio link control layer in the user side by using the media access control layer in the user side to produce traffic volume measurements, comparing the traffic volume measurements to at least one of an upper critical value and a lower critical value provided to the media access control layer in the user side from a radio resource control layer in a network side of the communication system through the radio resource control layer in the user side of the system, and forwarding a comparison result and the traffic volume measurements to the radio resource control layer in the network side through the radio resource control layer in the user side, and controlling the radio access bearer in the user side through the radio resource control layer in the network side according to a result of the comparison.

REFERENCES TO RELATED APPLICATIONS

[0001] This application claims priority from Korean Patent ApplicationNo. P1999-26688 filed on Jul. 2, 1999, the entirety of which is herebyincorporated by reference for all purposes as if fully set forththerein.

BACKGROUND OF THE INVENTION

[0002] 1. Field of the Invention

[0003] The present invention relates to a next generation mobilecommunication system, and more particularly, to in a method forcontrolling a radio access bearer in a next generation mobilecommunication system.

[0004] 2. Background of the Related Art

[0005] Recently, the Association of Radio Industries and Business (ARIB)in Japan, the European Telecommunications Standards Institute (ETSI) inEurope, the TI in the USA, the Telecommunications Technology Association(TTA) in Korea, and the TTC in Japan have planned a further evolved nextgeneration mobile communication system based both on the core networktechnology of the existing Global System for Mobile Communications (GSM)which serves for multimedia, such as audio, video and data, and radioaccess technology. These organizations have agreed on common researchfor suggesting a technical specification for the evolved next generationmobile communication system, a project named Third GenerationPartnership Project (3GPP). The 3GPP encompasses the following threetechnical research fields.

[0006] The first technical research field is the 3GPP system and servicefield, for researching system architectures and service capabilitiesbased on the 3GPP specification.

[0007] The second technical research field is the field of UniversalTerrestrial Radio Access Network (UTRAN). The UTRAN is a RAN (RadioAccess Network), including W-CDMA according to a Frequency DivisionDuplex (FDD) mode, and TD-CDMA according to a Time Division Duplex (TDD)mode.

[0008] The third technical research field pertains to a core networkhaving a third generation networking capability, such as mobilitymanagement and global roaming, being evolved from the second generationGSM.

[0009] Of the Technical Specification Groups (TSGs) conducting suchtechnical research, the Working Group 1 (WG1) related to Radio AccessNetworks (RAN) suggests general technologies for the physical layer(Layer 1), and the Working Group 2 (WG2), defines a data link layer(Layer 2) and a network layer (Layer 3), both being at higher levelsthan the physical layer, as a second radio layer (Radio Layer 2) and athird radio layer (Radio Layer 3), and suggests general technologies onthe second and third radio layers.

[0010]FIG. 1 illustrates a related art radio interface protocolarchitecture according to the 3GPP RAN. An air-interface protocolbetween UE (User Equipment) and a network side UMTS Terrestrial RadioAccess Network, UTRAN) consists of layer 1, radio layer 2, and radiolayer 3.

[0011] Referring to FIG. 1, a protocol architecture is divided into acontrol plane (C-Plane) for signaling, and a user plane (U-Plane) fortransmission of information. The C-Plane has a Radio Resource Control(RRC) Layer at Layer 3, and a Radio Link Control (RLC) Layer and aMedium Access Control (MAC) Layer at Layer 2, a layer lower than theLayer 3, and a Layer 1 at a lowest layer. The U-Plane has the RLC andMAC at Layer 2, and the Layer 1, a layer lower than the Layer 2. TheLayer 1 provides a transport channel for upper layer(s) inclusive of theMAC. In this instance, depending on how information is transferred onthe air-interface, different transport channels are provided, i.e.,either a common transport channel or a dedicated transport channel isprovided.

[0012] The MAC provides the upper RLC with logical channels, whichdiffer depending on the forms of information to be transported. That is,the MAC provides the data transfer service on the logical channels,forms of which logical channels differ depending on the kinds of thedata transfer services provided by the MAC. In this instance, the formsof theological channels differ depending on the forms of information tobe transported, wherein, in general, control channels are provided wheninformation for the C-Plane is to be transported, and traffic channelsare provided when information for the U-Plane is to be transported.Besides this, the MAC provides radio resource reconfiguration and MACparameter reconfiguration services, which are served when the RRCrequests a radio resource reconfiguration. or a MAC parameter change.The MAC also provides a measurement report service, reporting trafficvolume values, a service quality index, a MAC condition index, and thelike to the RRC. The MAC providing those services has many functions,including a traffic volume monitoring function which informs the RRC ofthe traffic volume on the logical channel. The RRC analyses trafficvolume information reported from the MAC, and determines switching forthe transport channels.

[0013] The RLC provides services for radio access establishment/orcancelation. The RLC also provides a service for transporting PDU(Protocol Data Units) at the upper layer to which any protocolinformation, inclusive of segmentation/reassembly functions, is notincluded. The RRC provides an information broadcast service, in whichinformation is broadcast to all UE in an one area. The RRC also controlsLayer 3 C-Plane signal processing between the UE and the UTRAN. That is,the RRC provides functions of establishment, sustenance, and cancelationof radio resource access between the UE and the UTRAN. Particularly, theRRC provides functions of establishment, sustenance, or cancelation ofradio access bearers, functions of assignment, reconfiguration, andcancelation of radio resources required for radio resource access (thebearer is a capability defined for a signal transfer on the radiointerface), and UE measurement report and report control functions,corresponding to the traffic volume monitoring function among thefunctions of the MAC. The measurements at the UE are controlled by theRRC, when the RRC informs the UE of an object, a time and a method ofthe measurement. Then, the RRC informs the UTRAN of the measurements atthe UE. The radio interface protocol layers explained up to now provideother various functions and services. In such an existing radiointerface protocol architecture, traffic volume at the RLC is monitoredat the MAC in the U-Plane, for the RRC to assign, sustain or cancelradio resources.

[0014] However, no detailed procedures for these functions are suggestedyet, in fact. That is, as explained, what is described in the 3GPP RANis only that a RLC traffic volume in a current user system is monitoredat the MAC, and only that radio access bearer control procedures, suchas bearer reconfiguration, and channel reconfiguration are carried outaccording to the traffic volume monitoring at the MAC, without anysuggestions or detailed procedures for carrying this out.

SUMMARY OF THE INVENTION

[0015] Accordingly, the present invention is directed to a method forcontrolling a radio access bearer in a mobile communication system thatsubstantially obviates one or more of the problems due to limitationsand disadvantages of the related art.

[0016] An object of the present invention is to provide a method forcontrolling a radio access bearer in a mobile communication system, forcontrolling a radio bearer according to traffic volume more accurately.

[0017] Another object of the present invention is to provide a methodfor controlling a radio access bearer in a mobile communication system,for efficient management of radio resources according to traffic volumein a radio interface protocol.

[0018] Additional features and advantages of the invention will be setforth in the description which follows, and in part will be apparentfrom the description, or may be learned by practice of the invention.The objectives and other advantages of the invention will be realizedand attained by the structure particularly pointed out in the writtendescription and claims hereof as well as the appended drawings.

[0019] To achieve these and other advantages and in accordance with thepurposes of the present invention, as embodied and broadly described, amethod for controlling a radio access bearer in a mobile communicationsystem, comprising: (1) disposing a radio resource control layer havingradio access bearers in a user side-of the communication system; (2)disposing a radio link control layer, a media access control layer, anda physical layer in the user, side beneath the radio resource controllayer in succession; (3) measuring a traffic volume of the media accesscontrol layer and radio link control layer in the user side by using themedia access control layer in the user side to produce traffic volumemeasurements; (4) comparing the traffic volume measurements to at leastone of an upper critical value and a lower critical value provided tothe media access control layer in the user side from a radio resourcecontrol layer in a network side of the communication system through theradio resource control layer in the user side of the system, andforwarding a comparison result and the traffic volume measurements tothe radio resource control layer in the network side through the radioresource control layer in the user side; and (5) controlling the radioaccess bearer in the user side through the radio resource control layerin the network side according to a result of the comparison.

[0020] It is to be understood that both the foregoing generaldescription and the following detailed description are exemplary andexplanatory and are intended to provide further explanation of theinvention as claimed.

BRIEF DESCRIPTION OF THE DRAWINGS

[0021] The accompanying drawings, which are included to provide afurther understanding of the invention and are incorporated in andconstitute a part of this specification, illustrate embodiments of theinvention and together with the description serve to explain theprinciples of the invention.

[0022] In the drawings:

[0023]FIG. 1 illustrates a diagram showing a related art radio interfaceprotocol architecture according to the 3GPP RAN;

[0024]FIG. 2 illustrates a diagram showing a system of protocol entitiesfor explaining a procedure for controlling an active radio access bearerin accordance with a preferred embodiment of the present invention;

[0025]FIG. 3 illustrates a diagram showing a procedure for monitoringtraffic volume for controlling an active radio access bcarer inaccordance with a preferred embodiment of the present invention;

[0026] FIGS. 4A-4C illustrate states of buffers in protocol entities forcontrolling an active radio access bearer in accordance with a preferredembodiment of the present invention;

[0027]FIG. 5 illustrates another system of protocol entities explaininga procedure for controlling an active radio access bearer in accordancewith a preferred embodiment of the present invention; and,

[0028]FIG. 6 illustrates a flow chart showing a process for monitoringtraffic volume for controlling an active radio access bearer inaccordance with a preferred embodiment of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

[0029] Reference will now be made in detail to the preferred embodimentsof the present invention, examples of which are illustrated in theaccompanying drawings. FIG. 2 illustrates a diagram showing a system ofprotocol entities for explaining a procedure for controlling an activeradio access bearer in accordance with a preferred embodiment of thepresent invention, particularly, a state before a transport channel isswitched in conducting traffic volume monitoring, and an initial stateof the MAC. The MAC is disposed by the RRC including radio accessbearers RAB1, RAB2 and RAB3 multiplexed into dedicated channels DCH1,and DCH2. The dedicated channels DCH1 are DCH2 are multiplexed into aCoded Composite Transport Channel (CCTrCH). After disposing the radioaccess bearers, the RRC disposes the lower three layers of the RLC,tkdr1, and MAC, and the physical layer (hereafter called as “PHY”). Whenthese lower three layers are disposed, the RRC provides a disposalrequest primitive CMAC_configure_REQ to the MAC, which includes: first,radio access bearer identification (ID), second, a logical channel ID,which is multiplexing information, a transport channel ID, and a logicalformat priority according to a service quality (QoS), and third, atransport format combination set, which is transport channelinformation. Upon completion of disposal of the lower three layers, theRRC requests the MAC to carry out a traffic volume monitoring function.

[0030]FIG. 3 illustrates a flow of messages showing a procedure formonitoring traffic volume in accordance with a preferred embodiment ofthe present invention.

[0031] Referring to FIG. 3, before the process for monitoring trafficvolume, the UTRAN-RRC provides a system information message to theUE-RRC through a BCCH (Broadcasting Control Channel) (S1), and aMEASUREMENT CONTROL message through a Digital Control Channel (DCCH).(S2). Eventually, the UE-RRC can have parameters required for thetraffic volume measurement. Then, the UE-RRC requests the UE-MAC tocarry out the traffic volume monitoring (S3). In this instance, theUE-RRC provides the UE-MAC with a primitive CMAC_MEASUREMENT_REQ,containing a measurement report mode parameter, and a measurement periodparameter. If the measurement report mode is a periodic mode, a reportinterval parameter is added thereto, and if the measurement report modeis an event trigger mode, an upper critical value TH_(U) parameter and alower critical value TH_(L) parameter are added thereto. The uppercritical value TH_(U) parameter denotes a greatest boundary trafficvolume in reporting measurements to UE-MAC, and the lower critical valueTH_(L) parameter denotes a smallest boundary traffic volume in reportingmeasurement to the UE-MAC. Then, the UE-RLC provides the UE-MAC withstates of respective buffers, and its own data through the primitiveRLC_DATA_REQ at fixed intervals (S4). In this instance, as shown in FIG.2, respective buffers are at transport RLC buffer 1, 2, and 3 states,and data inclusive of the respective buffer states are provided througha dedicated traffic channel (DTCH). If the present measurement reportmode is a periodic mode, the UE-MAC receives results of measurements atthe transport RLC buffers 1, 2, and 3, and results of measurements atits transport MAC buffers 4, and 5, and provides these to the UE-RRC,periodically. (S5). Conversely, if the present measurement report modeis an event trigger mode, the UE-MAC checks if the results ofmeasurements at the transport RLC buffers 1, 2, and 3, and the resultsof measurements at its own transport MAC buffers 4, and 5 either exceedthe upper critical value TH_(U) or are lower than the critical valueTH_(L). If the results are outside the bounds TH_(U) and TH_(L), thenthey are reported to the UE-RRC (S5).

[0032] In the foregoing step S5, the UE-MAC uses the primitiveCAMC_MEASUREMENT_IND, together with the following parameters inreporting to UE-PRC. First, a sum of data existing at the transport RLCbuffers 1, 2, and 3, and the transport buffers 4, and 5 corresponding tothe traffic volume transported through the CCTrCH of the PHY is used. Inother words, a sum of data existing at buffers of all transport channelsand all data existing at buffers of logical channels, multiplexed by theCCTrCH, is used. The sum of data forms the measurement results reportedto the UE-RRC described in the step S5. As other parameters, states ofrespective buffers the UE-RLC provides to the UE-MAC at every intervalthrough the primitive RLC_DATA_REQ are used. That is, the amounts ofdata corresponding to respective radio access bearers RAB1, RAB2, andRAB3 are used. In this instance, as statistic values obtained bymeasuring respective buffer data for a given time period, averages anddeviations of amounts of data existing at respective buffers are used.As another parameters, averages and deviations of amounts of traffictransported through respective transport channels, and statistics ofmeasurement of respective channels for a given time period are used.

[0033] Then, upon reception of the measurement results on the bufferstates from the UE-MAC, the UE-RRC provides the measurement results onthe buffer states to the UTRAN-RRC (S6). In this instance, themeasurement results are provided through the DCCH, and primitiveMEASUREMENT_REPORT_MESSAGE is used.

[0034] Finally, the UTRAN-RRC controls the radio access bearer withreference to, or according to, a result of the report of the measurementresults.

[0035] The radio access bearers may be controlled by bearerreconfiguration, transport channel reconfiguration, physical channelreconfiguration, and TFC (Transport Format Combination) (S7). The bearerreconfiguration is required for correcting transport channels of theRLC, and MAC, and a configuration of the PHY entirely, and the transportchannel reconfiguration is required for correcting the transport channelof the MAC and a configuration of the PHY. The physical channelreconfiguration is also required for correcting a configuration of thePHY. Thus, upon completion of the procedure for controlling the radioaccess bearers, the UTRAN_RRC provides new critical values to theUE-RRC, and the UE-RRC provides the new critical values to the UE-MAC.According to this, the MAC uses the new critical values provided theretoin carrying out the traffic volume monitoring function. By the way, ifthe received critical value drops below a specific level continuouslywhile the MAC carries out the traffic volume monitoring functioncontinuously and MAC receives the new critical values continuously, thetransport channel type is changed from a Dedicated Channel (DCH) to aRandom Access Channel (RACH). That is, the form or type of transportchannel is switched.

[0036] FIGS. 4A-4C illustrate how states of buffers in protocol entitiesin a traffic volume monitoring process change with time. FIG. 5illustrates the radio interface protocol architecture after theswitching of a transport channel type occurs in the traffic volumemonitoring process. From FIG. 5, it can be seen that the PDU (ProtocolData Unit) of the RLC is transported, not through the dedicated MAC(MAC-d), but through a common MAC (MAC-c).

[0037]FIG. 6 illustrates a flow chart showing a process for monitoringtraffic volume for controlling radio access bearers in accordance with apreferred embodiment of the present invention. In order to makeexplanation of FIG. 6 clearer, the explanation also will refer to FIGS.2-5.

[0038] First, the MAC is provided with measurement parameters, inclusiveof the upper critical value TH_(U) and the lower critical value TH_(L)provided from the RRC (S10). Basically, the MAC is provided with a RLCPDU from each of the RLCs which transports different radio accessbearers RAB1, RAB2, and RAB3, and, at the same time, a state of each ofthe transport RLC buffers 1, 2, and 3 corresponding to respective radioaccess bearers from the RLC. Then, the MAC measures the a sum of dataexisting at the transport RLC buffers 1, 2, and 3, and the transport MACbuffers 4, and.5, which corresponds to the traffic volume transportedthrough the CCTrCH (S11). Then, the MAC compares the traffic volumemeasurement of the channel CCTrCH to the upper critical value TH_(U) andthe lower critical value TH_(L) provided from the RRC (S12). If themeasured traffic volume of the channel CCTrCH is a value falling betweenthe upper critical value TH_(U) and the lower critical value TH_(L), thetraffic volume measurement of the channel CCTrCH is measured at fixedintervals (for example, at every 10 ms). However, if the traffic volumemeasurement of the channel CCTrCH falls outside of the range between theupper critical value TH_(U) and the lower critical value TH_(L), thenthe result of the traffic volume measurement of the channel CCTrCH isprovided to the RRC (S13). Then, the RRC undertakes a procedure forcontrolling the radio access bearers based on the traffic volumemeasurement of the channel CCTrCH provided thereto. The procedure forcontrolling the radio access bearers has been explained already.

[0039] As has been explained, the method for active control of a radioaccess bearer in a mobile communication system of the present inventionhas the following advantages.

[0040] A procedure for controlling radio access bearers is provided inmore detail over the traffic volume monitoring. Therefore,establishment, sustenance, and cancelation of radio resource access canbe carried out efficiently in the radio interface protocol architectureaccording to traffic volumes of the RLC and MAC, which are sub-layers ofthe second layer.

[0041] And, the functions of establishment, sustenance, and cancelationof the radio access bearers and the radio resources required for radioresource access can be carried out more efficiently.

[0042] It will be apparent to those skilled in the art that variousmodifications and variations can be made in the method for controlling aradio access bearer in a mobile communication system of the presentinvention without departing from the spirit or scope of the invention.Thus, it is intended that the present invention cover the modificationsand variations of this invention provided they come within the scope ofthe appended claims and their equivalents.

What is claimed is:
 1. A method for controlling a radio access bearer ina mobile communication system, comprising: (1) disposing a radioresource control layer having radio access bearers in a user side of thecommunication system; (2) disposing a radio link control layer, a mediaaccess control layer, and a physical layer in the user side beneath theradio resource control layer in succession; (3) measuring a trafficvolume of the media access control layer and radio link control layer inthe user side by using the media access control layer in the user sideto produce traffic volume measurements; (4) comparing the traffic volumemeasurements to at least one of an upper critical value and a lowercritical value provided to the media access control layer in the userside from a radio resource control layer in a network side of thecommunication system through the radio resource control layer in theuser side of the system, and forwarding a comparison result and thetraffic volume measurements to the radio resource control layer in thenetwork side through the radio resource control layer in the user side;and (5) controlling the radio access bearer in the user side through theradio resource control layer in the network side according to a resultof the comparison.
 2. A method as claimed in claim 1, wherein trafficvolume comprises a sum of data at buffers of all transport channels andall data existing at buffers of all logical channels, both beingmultiplexed into a coded composite transport channel.
 3. A method asclaimed in claim 1, wherein the upper and lower critical values may bevaried as the steps (3) and (4) are repeated.
 4. A method as claimed inclaim 3, wherein, if the varied lower critical value drops below aparticular level, a transport channel can be switched from a firsttransport channel type to a second transport channel type.
 5. A methodas claimed in claim 4, wherein the first transport channel type is adedicated channel, and the second transport channel type is a randomaccess channel.
 6. A method as claimed in claim 1, wherein the step (5)includes the step of correcting a configuration of the physical layerchannels according to the comparison result.
 7. A method as claimed inclaim 1, wherein the step (2) includes the step of the radio resourcecontrol layer in the user side transporting a disposal request primitiveto the media access control layer, the disposal request primitive havinga radio access bearer ID, a logical channel ID which is multiplexinformation, a transport channel ID, and information on a logicalchannel priority dependent on a service quality, and a transport formatcombination set which is channel information.
 8. A method as claimed inclaim 1, further comprising the radio resource control layer in thenetwork side transporting a system information message through abroadcasting control channel, and a measurement control message througha dedicated control channel, to the radio resource control layer in theuser side, for providing the radio resource control layer in the userside with parameters required for the traffic volume measurements beforethe step (3).
 9. A method as claimed in claim 8, further comprising thestep of the radio resource control layer in the user side transporting aprimitive for requesting monitoring of the traffic volume to the mediaaccess control layer in the user side after reception of all theparameters, the primitive having a measurement report mode parameteridentifying a measurement report mode, and a measurement periodparameter.
 10. A method as claimed in claim 9, wherein the primitivefurther includes a report interval parameter when the measurement reportmode is a periodic mode, and an upper critical value and a lowercritical value when the measurement report mode is an event triggermode.
 11. A method as claimed in claim 10, wherein the upper criticalvalue represents a greatest boundary traffic volume, and the lowercritical value represents a smallest boundary traffic volume, both forthe media access control layer in the user side to report the trafficvolume measurements.
 12. A method as claimed in claim 9, wherein, whenthe present measurement report mode is a periodic mode, the media accesscontrol layer transports measurement results at transport buffers in theradio link control layer and measurement results of its own transportbuffers to the radio resource layer in the user side periodically, andconversely, when the present measurement report mode is an event triggermode, the media access control layer in the user side compares a sum ofmeasurement results at the transport buffers in the radio link controllayer and measurement results at its own transport buffers to the uppercritical value and the lower critical value, and reports the comparisonresult to the radio resource control layer in the user side.
 13. Amethod as claimed in claim 1, wherein a primitive is used when the mediaaccess control layer in the user side reports the traffic volumemeasurements, and a total amount of data existing at transport buffersin the radio link control layer and transport buffers in the mediaaccess control layer is used as a parameter.
 14. A method as claimed inclaim 13, wherein totals, an average, and deviations of data existing atbuffers of respective radio access bearers are used as other parameters.15. A method as claimed in claim 13, wherein traffic volumes transportedon respective transport channels, averages and deviations which arestatistics of the traffic volumes are used as other parameters.
 16. Amethod as claimed in claim 1, wherein the radio resource control layerin the user side receives the traffic volume measurements and thecomparison result from the media access control layer in the user side,and transports the traffic volume measurements and the comparison resultto the radio resource control layer in the network side by using theprimitive through a dedicated control channel.
 17. A method as claimedin claim 1, wherein controlling the radio access bearer includes: bearerreconfiguration in which all configurations of the radio link controllayer, media access control layer, and physical layer in the user sideare revised; transport channel reconfiguration in which media accesscontrol layer configurations and physical layer configurations arerevised; and physical channel reconfiguration in which a configurationof the physical layer in the user side is revised.